The zip file is incorrectly formatted. You need to put all the files in the zip file, in a subfolder named Meowdiver.pdx
Such as : Meowdiver.pdx.zip / Meowdiver.pdx / All the files
In contrary to the current : Meowdiver.pdx.zip / All the files
Thanks for pointing that out! I’ve re-uploaded the zip. It now contains a Meowdiver.pdx folder with all the files inside, so sideloading should work.